Process for the production of artificial bristles and the like from proteins



Patented Sept. 12, 1950 UNITED STATES PATENT 'OFFlCE 2.5mm rao'cs'ss 'roa 'rns raonuc'rrou or Ann- I noun. nars'ru-zs rao'rams ANDTHE LIKE FROM tary of Agriculture No Drawing. Application June 15, 1944, Serial No. 540,504

(Granted under the act of March 3, 1883, as amended April 30. 1928; 370 0. G. 757) Claims.

This application is made under the act of March 3, 1883, as'amended by the act of April 30, 1928, and the invention herein described, if patented, may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment to us of any royalty thereon.

This invention relates to the production of artificial bristles from proteins which are useful in making various types of commercial brush-' es, and tor similar uses, such as stufilng for furniture, and so forth. In this connection, the term "bristle" as herein employed includes all types of animal hair having commercial use, such as pig bristle, horsehair, camel hair, et cetera. These materials are known to have a wide variety of uses such as in brushes of many kinds, stuillng for furniture and stiifeners in clothing. It is further understood that characteristic properties of such bristles and hair which contribute materially to practical use are: tensile strength, flexibility, resilience, durability, inertness to oils and organic solvents and low water uptake.

Our method of producing artificial bristles of this type comprises mixing a protein such as finely divided commercial iso-electric casein (80- 100 mesh) with about 80 to 100 percent of its weight of water (although other proportions are not excluded) and kneading the mixture in a mechanical mixer at 80 to 100 C. for about 5 to minutes until a homogeneous plastic gel is obtained. This plastic material is then converted into fibers by pressing it, at a temperature of 95 to 110 0., through a die having holes of a desired diameter. Orifice diameters of from 0.1 to 1.0 mm. can be satisfactorily used. The fibers are extruded into air andvpassed over rotating drums so that the fiber is stretched. The ilber is then passed rapidly through a solution containing 2 percent formaldehyde, 0.1 percent of a naphthalene sulfonate or other wetting agent. and 10 percent sodium sulfate to minimize the tendency of the fibers to stick together. An alternative procedure for preventing sticking of the newly formed fiber is to dry it. before reeling. by exposure to a current of hot air or to infra-red lamps. The fibers are then wound on a suitable reel.

The fiber is next cut oil the reel in suitable lengths and is given a short chemical hardening treatment until it has acquired sufilcient strength to permit it to be stretched to two or three times its original length. The hardening bath may conany concentration up to a saturated solution or of formaldehyde at preferably a 2 percent'concentration. The hardening may be carried out at room temperature, or at a higher temperature it it is desirable to shorten the period of hardening. After this hardening treatment, the fiber is progressively stretched by any suitable means to a length 50 percent to 200 percent, or more, greater than its initial length, and is. held in this stretched condition while it is again replaced in the hardening bath for a sufilcient period for the fiber to attain its maximum water resistance. The time required for the second hardening treatment when a 1 percent solution of p-benzoquinone at room temperature is used is from 24 to 40 hours. After hardening the fiber is removed from the bath and dried while the tension is maintained. The hardening agents, p-benzoquinone or formaldehyde, may be used alone. or both may be used in simultaneous or successive treatment as of stretch imparted to the fiber.

The use of p-benzoquinone results in a black fiber while formaldehyde 4 gives a white fiber. Greater water resistance is given by p-bensoquinone than by formaldehyde, but the combined efiect oi p-benzoqulnone followed by formaldehyde is greater than that of either one used alone. The strength of the fiber increases as greater amounts of stretch are Riven the fiber, but the fiber obtained after application of the greatest practicable amount of stretch tends to be more brittle than fiber given less stretch. For example, the application of the maximum stretch yields a fiber with a tensile strength of 1.2 grams per denier. The tensile strength of a fiber with a loop tied in it which may be taken as a measure of the flexibility reaches a maximum of about 0.7 gram per denier when the tensile strength of a straight piece is about 0.8 gram per denier. The amount of stretch given the fiber will therefore depend on whether strength or flexibility is the more desirable characteristic in the particular use for which the fibers are intended.

The further application of our invention to bristles other than casein is illustrated by the following examples:

Example I Purified and finely divided soybean protein, such as alpha soybean protein, was mixed with sist of an aqueous solution of p-benzoquinone at as from to percent of its weight of water and kneaded at 80 to 100 C. for to minutes. producing a plastic gel. Fibers were then made from this plastic material by the above-described method. Bristles prepared from soybean fiber are quite serviceable, but their flexibility and tensile strength are only approximately 80 percent oi. corresponding values for bristles prepared from casein.

Example II Purified ground zein was mixed with from to 80 percent of its weight of water and kneaded at 80 to 100 C. for 5 to 10 minutes, producing a plastic gel. Fibers were then made by the abovedescribed method. Bristles made from zein have good tensile strength and stiffness, but are somewhat more brittle than bristles made from casein.

Example III Finely divided commercial gelatin was mixed with from to 90 percent 01' its weight of water and kneaded at to 100 C. for 5 to 10 minutes, producing a plastic gel. Fibers were then made by the above-described method, except that the fibers were not allowed to come in contact with solutions since water would disintegrate them. The gelatin fibers were rendered insoluble'by allowing them to stand for 48 hours in gaseous formaldehyde. Gelatin fibers cannot be hardened in aqueous solutions of quinone, because of their solubility.

The solubility of gelatin fibers in aqueous so lutions of hardening agents makes it desirable to mix this protein with casein before kneading and extrusion. Such fibers containing from 50 to percent casein can be hardened in both formaldehyde and quinone solutions. The strength and flexibility of the bristles made from mixtures of gelatin and casein are of the same order as that of the bristles from pure casein.

In summary, our invention comprises treating an extruded and stretched protein filament with a hardening agent while being further stretched. In its preferred form the said protein filament is chemically unmodified protein; for example, isoelectric protein.

Cross-reference is made to our co-pending application, Serial No. 584,487, filed March 23, 1945, now abandoned.

Having thus described our invention, we claim:

1. A process of making a fiber having a tensile strength of at least about 0.8 gram per denier, comprising: kneading a mixture essentially consisting of water and iso-electric casein at about 80 to C. until a homogeneous plastic mass is obtained; forming a filament by extruding the said mass at 95 to C. into air; stretching the so extruded chemically unmodified filament;

subjecting the stretched fiber to treatment with an anti-sticking agent; then subjecting thefilament to a hardening bath; stretching the hardened filament to a length at least fifty percent greater than its original length; and while in stretched condition again subjecting the filament to the action of a hardening bath; and drying the filament while under tension.

2. The process of claim 1 in which the hardening baths comprise a solution of p-benzoquinone. 3

3. A process of making a fiber comprising: kneading a hot mixture essentially consisting of water and iso-electric casein until a homogeneous plastic mass is obtained; forming a filament by extrudin the said hot mass into air; stretching the so extruded and chemically unmodified filament; subjecting the stretched filament to treatment with an anti-sticking agent; stretching the filament to a length at least about filty percent of its original length; subjecting the filament while in stretched condition to a hardening bath; and drying the filament while under tension.

4. The process of claim 3 in which the hardening bath is a solution of p-benzoquinone.

5. The process of claim 3 in which the hardening bath is a solution of formaldehyde.

THOMAS L. McMEEKIN. THOMAS S. REID. ROBERT C. WARNER. RICHARD W. JACKSON.

REFERENCES CITED The following references are of record in the tile of this patent:

UNITED STATES PATENTS Number Name Date 998,370 Meunier July 18, 1911 2,103,138 Becker et al Dec. 21, 1937 2,120,851 Becker et al. June 14, 1938 2,169,955 Koch Aug. 15, 1939 2,207,158 Neville et al July 9, 1940 2,233,885 Kratz et a1 Mar. 4, 1941 2,266,672 Wormell Dec. 16, 1941 2,290,789 Wormell July 21, 1942 2,354,077 van Bergen July 18, 1944 2,361,713 Sturken Oct. 31, 1944 2,389,292 Bjorksten Nov. 20, 1945 2,404,665 Signer July 23, 1946 2,429,214 Biehn et al Oct. 21, 1947 OTHER REFERENCES Rogers: Practical Tanning; 1922 Lockwood and Son, London, pages 563 and 564.

Trotman: J. Soc. Chem. Ind.; Dec. 25, 193 page 466T.

McLaughlin et al.: Chem. of Leather Mir. 1945; Reinhold Pub. Corp., N'. Y., page 388. 

1. A PROCESS OF MAKING A FIBER HAVING A TENSILE STRENGTH OF AT LEAST ABOUT 0.8 GRAM PER DENIER, COMPRISING: KNEADING A MIXTURE ESSENTIALLY CONSISTING OF WATER AND ISO-ELECTRIC CASEIN AT ABOUT 80 AND 100*C. UNTIL A HOMOGENEOUS PLASTIC MASS IS OBTAINED: FORMING A FILAMENT BY EXTRUDING THE SAID MASS AT 95 TO 110*C. INTO AIR; STRETCHING THE SO EXTRUDED CHEMICALLY UNMODIFIED FILAMENT; SUBJECTING THE STRETCHED FIBER TO TREATMENT WITH AN ANTI-STICKING AGENT; THEN SUBJECTING THE FILAMENT TO A HARDENING BATH; STRETCHING THE HARDENED FILAMENT TO A LENGTH AT LEAST FIFTY PERCENT GREATER THAN ITS ORIGINAL LENGTH; AND WHILE IN STRETCHED CONDITION AGAIN SUBJECTING THE FILAMENT TO THE ACTION OF A HARDENING BATH: AND DRYING THE FILAMENT WHILE UNDER TENSION. 